Authors' objectives: We conducted a systematic review of the evidence on the use of low-dose aspirin for the prevention of morbidity and mortality from preeclampsia to support the U.S. Preventive Services Task Force (USPSTF) in updating its previous recommendation. Prior reviews have established that benefits of aspirin prophylaxis are not obtained in populations of healthy or unselected pregnant women not at high risk of preeclampsia. In this review we considered the evidence on benefits and harms of low-dose aspirin for women at elevated risk of developing preeclampsia and consequent maternal and fetal health outcomes. Three key questions (KQs) were systematically reviewed: 1) Is there evidence that aspirin reduces adverse maternal or fetal health outcomes? 2) Is there evidence that aspirin reduces incidence of preeclampsia? and 3) What are the harms of low-dose aspirin use during pregnancy?

Authors' recommendations: For women at elevated risk of pre-eclampsia, prophylaxis with low-dose aspirin (60 to 150 mg) beginning after the first trimester of pregnancy reduced risk of pre-eclampsia and important adverse perinatal health outcomes. Specifically, modestly reduced risks of preterm birth, IUGR, and possibly perinatal mortality were supported by the evidence. Consistent with lower risk of preterm birth and IUGR, a significant difference in birth weight was also present. Statistical significance was not attained for the estimated 19 percent reduction in risk of perinatal mortality, although power to detect this difference was under 50 percent; there is a risk of incorrectly accepting a null result for perinatal mortality based on currently available data. The effects on perinatal mortality observed in the two largest trials were consistent with a benefit, although more modest. The pooled results finding reduced risk of pre-eclampsia with low-dose aspirin supports the causal pathway leading to the observed direct health outcomes. The pooled results may have overestimated the benefit, however, given the evidence of small-study effects and more modest results in the two largest trials. However, given the consistency of the effect size in the large trials and the results of pooled analysis, at least a 10 percent reduction in pre-eclampsia was supported by the evidence. This reduction in pre-eclampsia incidence likely underlies the observed perinatal health benefits. There was limited evidence of harms associated with low-dose aspirin use during pregnancy. A potential increased risk of abruption could not be ruled out, but evidence of harm from other bleeding-related complications, such as postpartum hemorrhage, maternal blood loss, and neonatal intracranial or intraventricular bleeding was not found. The evidence on longer-term outcomes for offspring from in utero aspirin exposure (low-dose) is very limited, but followup data from one large randomized, controlled trial is reassuring.

Project Status: Completed

Year Published: 2014

URL for published report: http://www.ncbi.nlm.nih.gov/books/NBK196392/pdf/TOC.pdf

URL for additional information: http://www.ncbi.nlm.nih.gov/books/NBK196392/

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: United States

Organisation Name: Agency for Healthcare Research and Quality

Contact Address: Center for Outcomes and Evidence Technology Assessment Program, 540 Gaither Road, Rockville, MD 20850, USA. Tel: +1 301 427 1610; Fax: +1 301 427 1639;

Contact Name: martin.erlichman@ahrq.hhs.gov

Contact Email: martin.erlichman@ahrq.hhs.gov

Copyright: Agency for Healthcare Research and Quality (AHRQ)